The present invention relates generally to capillary measuring and detecting devices, and more particularly, to a sealing device and method for the inhibition of liquid flow in capillary measuring devices, especially in capillary based diagnostic measuring devices.
Typically, the devices of the present invention have a chamber, e g., a capillary chamber or channel, which fills with a liquid by capillary and/or other action, and the liquid is metered into all parts of the device. In one such class of capillary devices, once the capillary chamber or capillary channel is filled with liquid, it is very important to inhibit or prevent further movement of the liquid. Any such movement of liquid can potentially disturb any analytical reading for which the device is used.
Capillary measuring devices are well-known and have wide utility in the field of analytical diagnosis. Capillary measuring devices are described in U.S. Pat. Nos. 5,032,506 and 5,036,000, both of which are incorporated by reference herein in their entirety. These patents describe a capillary measurement system based on a dehydrogenase based analog-to-digital switch suitable for the measurement of numerous metabolic substances, which is particularly adaptable to the measurement of alcohol from a saliva sample. A product based on this technology is commercially available from Enzymatics, Incorporated and is identified as the Q.E.D. Saliva Alcohol Test.
In U.S. Pat. No. 5,126,247 filed Feb. 26, 1988, now allowed, which is incorporated by reference herein in its entirety, there is described a method, system and device for the assay and detection of biochemical molecules. Disclosed and described therein is a capillary measuring device based on oxidation of a substrate by an enzyme capable of transferring electrons to an aromatic or anti-aromatic acceptor, which is particularly adaptable to measurement of cholesterol from a fingerstick drop of blood.
In the above-identified patents and patent application, there is a threshold gradient maintained along the capillary The capillary is filled with analytical sample without disturbing the gradient. After filling the capillary, the reagents that produce the gradient dissolve into the liquid sample and are present in a gradient along the length of the capillary. This gradient would be disturbed if the liquid stream was capable of additional movement, for example, by capillary action, and any movement of the gradient stream could result in error in the analysis determined in the analytical device. In view of the foregoing, it can be seen that it would be highly desirable to prevent such movement of the liquid in the capillary device.
In U.S Pat. No. 5,087,556, which is incorporated by reference herein in its entirety, a method is described for the quantitative analysis of body fluid constituents by a self-contained, chromatic quantitative analyzer that quantitatively detects an analyte in a biological fluid. This patent describes a base having a first open reservoir for receiving biological fluid; a means for separating solids from the biological fluid in the first open reservoir; a channel for drawing by capillary and/or wicking action, the biological fluid from the first open reservoir to a second open reservoir, wherein the second open reservoir draws the biological fluid from the channel, and, when the second open reservoir is full of biological fluid, the capillary and/or wicking action terminates. The means for metering the biological fluid is complex, and a "pull" compartment or a second open reservoir filled with an absorbent is used as the means for metering the biological fluid. The geometry, physical nature and method of incorporation of the "pull" compartment and the channel must be configured to precisely meter the volume and rate of flow of the biological fluid through the channel. Thus, this device utilizes a complex arrangement and system for precise metering.
In view of the foregoing, it can be seen that simplified metering and control systems are desirable for inhibiting or controlling the flow of liquids, for example, biological fluids, in capillary measuring devices.